fix: do not crash on fetch(new Request(url)) (#1274)

* fix: do not crash on fetch(new Request(url)) * chore: fix headers type
open-telemetry · Jul 8, 2020 · 264fb36 · 264fb36
1 parent 7cce64f
commit 264fb36
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Showing 2 changed files with 19 additions and 7 deletions.
diff --git a/packages/opentelemetry-plugin-fetch/src/fetch.ts b/packages/opentelemetry-plugin-fetch/src/fetch.ts
@@ -98,7 +98,7 @@ export class FetchPlugin extends core.BasePlugin<Promise<Response>> {
    * @param options
    * @param spanUrl
    */
-  private _addHeaders(options: RequestInit, spanUrl: string): void {
+  private _addHeaders(options: Request | RequestInit, spanUrl: string): void {
     if (
       !web.shouldPropagateTraceHeaders(
         spanUrl,
@@ -107,9 +107,16 @@ export class FetchPlugin extends core.BasePlugin<Promise<Response>> {
     ) {
       return;
     }
-    const headers: { [key: string]: unknown } = {};
-    api.propagation.inject(headers);
-    options.headers = Object.assign({}, headers, options.headers || {});
+
+    if (options instanceof Request) {
+      api.propagation.inject(options.headers, (h, k, v) =>
+        h.set(k, typeof v === 'string' ? v : String(v))
+      );
+    } else {
+      const headers: Partial<Record<string, unknown>> = {};
+      api.propagation.inject(headers);
+      options.headers = Object.assign({}, headers, options.headers || {});
+    }
   }
 
   /**
@@ -242,8 +249,7 @@ export class FetchPlugin extends core.BasePlugin<Promise<Response>> {
         init?: RequestInit
       ): Promise<Response> {
         const url = input instanceof Request ? input.url : input;
-        const options: RequestInit =
-          input instanceof Request ? input : init || {};
+        const options = input instanceof Request ? input : init || {};
 
         const span = plugin._createSpan(url, options);
         if (!span) {

diff --git a/packages/opentelemetry-plugin-fetch/test/fetch.test.ts b/packages/opentelemetry-plugin-fetch/test/fetch.test.ts
@@ -117,7 +117,7 @@ describe('fetch', () => {
     sandbox.stub(core.otperformance, 'timeOrigin').value(0);
     sandbox.stub(core.otperformance, 'now').callsFake(() => fakeNow);
 
-    function fakeFetch(input: RequestInfo, init: RequestInit = {}) {
+    function fakeFetch(input: RequestInfo | Request, init: RequestInit = {}) {
       return new Promise((resolve, reject) => {
         const response: any = {
           args: {},
@@ -459,6 +459,12 @@ describe('fetch', () => {
       );
     });
 
+    it('should set trace headers with a request object', () => {
+      const r = new Request('url');
+      window.fetch(r);
+      assert.ok(typeof r.headers.get(core.X_B3_TRACE_ID) === 'string');
+    });
+
     it('should NOT clear the resources', () => {
       assert.strictEqual(
         clearResourceTimingsSpy.args.length,